If you don't need to store the contents of the file, try this:

open (FILE, "edidocs.csv") or die "Can't open file $!\n";

my( $curr_time, $prev_time );  # Sorry about the $ in the original
while( <FILE> ) {
    $prev_time = $curr_time;
    $curr_time = ( split /,/ )[1];
}
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If you do need to store the whole file, then the last two lines are stored in $lines( $#lines - 1 ) and $lines( $#lines ) of your example before you popped them off the stack.

elbieelbieelbie